1. Field of the Invention
The present invention pertains to the field of orthopaedics and relates more particularly to an external fixator which is intended for the consolidation of a long bone fractured towards its end.
2. Description of the Prior Art
For many years now, development work has been carried out on external fixators whose components are put into place after the pins have been inserted in the optimum position in relation to the bone fragment, which is to be maintained, and to the tissue surrounding it. Hinge elements provide for the connection between the pins and the immobilizing rod or rods, so as to ensure their relative orientation.
The Applicant has specifically developed for this purpose the hinge element which is described in U.S. patent application Ser. No. 08/788,718, filed Jan. 24, 1997, the teachings of which are incorporated herein by reference and which permits orientation either of a pin and a rod or of two rods. This hinge element includes several pairs of jaws forming grooves which are positioned and disposed in such a way as to present an external opening which allows the cylindrical component or rod to be snapped into place by means of pressing them against to the elastic or spring means. The spring presses the adjacent faces of the jaws against the cylindrical components prior to the hinge element being locked.
In some cases it is necessary to use a fixator which includes a single immobilizing frame. For this type of fixator, pairs of at least two bone pins are inserted on either side of the fracture and are indirectly fixed to the ends of an immobilizing rod. When a long bone is fractured near a joint, it is preferable to insert the pins in what is called a "T" arrangement, some of the pins being inserted in the epiphysis in a plane perpendicular to the bone, the others being inserted in the central part of the bone, in a plane containing the fractured bone. Each group of pins is held in a vice which can be oriented in relation to the immobilizing rod by means of a hinge or a ball joint.